Back to the Future? Back to the drawing board


Reports that time travel has been proven impossible may be somewhat overstated, but it’s certainly looking unlikely.

The main argument against time travel is based on the fact that the speed of light is fixed and that nothing can travel faster: in effect, it’s the speed limit of the universe. The explanation for the limit is that it would take an infinite amount of energy for an object to accelerate to the speed of light and thus there’d be no way to take that extra step to what’s known as superluminal travel.

That limitation blocks one theory of time travel: that the effect of an event could travel faster than light, such that it appeared before the cause of the event. (Exploiting this disparity to allow time travel is a separate issue of course.)

There have been plenty of theories about how objects could travel faster than the speed of light, most of which are in mindbending territory, but there are two common themes: scientists usually describe such superluminal travel merely as “apparent” or “effective”, and they usually say it would have to involve abnormal conditions.

There have been studies of photons, the particle which is the basis of light, in which a group of photons appear to travel faster than the speed of light. However, Professor Shengwang Du of the Hong Kong University of Science and Technology, says that in this situation there’s no way for the photons to actually carry any information.

Du has now carried out experiments involving single photons. He split the main body of a photon from its optical precursor, which the BBC likens to “the wind that moves ahead of a speeding train.” He then found that in a vacuum, the precursor is still limited to the speed of light, and that the main body of the photon cannot travel faster.

Of course, the idea of time travel still has support, but it looks like we’re going to have to start literally ripping-up the space-time continuum and creating wormholes. That might seem quite a stretch in the month that NASA shuttle missions ended, but if we stick a bit of cash in a high-interest savings account now, then surely when we arrive in the future there should be enough there to pay the bills.

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14 Responses to Back to the Future? Back to the drawing board

  1. Well, we've always been able to go forward in time. For example… if the they then did, such that when the who that did the upon who was in that which did to their hence upon. They, the upon-them when they thus thought that they could travel through time, found that it was only possible to travel forward in time, and that it's not possible to travel BACK in time and re-gain those 20-odd seconds of yours that I just wasted.

    Because if you COULD travel backwards in time, there is no doubt you would be, just to get those wasted seconds back. ;)

  2. ooh heres my pseudo-sciency rant for today, time travel in the conventional sense is impossible, the past present and future all exist at the same time, albeit in separate dimensions there are an infinite number of dimensions, and every action no matter how minute creates another. you cannot go back in time and kill your mother and prevent yourself from being born, that would be paradox, nature abhors it, so instead you go to an alternate dimension identical to this one, and kill your mother thus preventing that version of you from being born, it would have no affect on your "home" dimension. my theory is that gravity and/or energy is a side effect of the the act of these dimensions being continuously created. since the "multi-verse" is infinite you can go to any dimension representing a specific time or place that you can imagine, infinite universes, infinite possibilities! the trick is how to reference your origin point with a specific universe within the multi-verse and to then go there and back, since there are an infinite number of dimensions how do you choose? with each action you make you create more! this rant has been brought to you by me!

  3. My gripe with this article is that it states that the speed of light is fixed. It's not: variables such as temperature can affect it; in fact some labs have been able to bring light to a virtual standstill by achieving a temperature relatively close to absolute zero. I tend to get a little annoyed when people ignore the science and act as though the speed of light is a constant variable.

    • They should have been more specific, but it's obvious to me that they meant the speed limit c and not a local limit affected by the medium. But i do share the complaint in general that people don't realize light doesn't always (or even usually) travel at c. Moreover that we can and have made things propagate much faster than c; just not in a way that can transmit information.

  4. Well, it's only after disproving the theories that are wrong that you get to the ones that are right, right? :P

  5. 1) The main argument against traveling back in time is ofcause that you could kill our own mother, never have been born = Paradox – physics and paradoxes dont often go hand in hand. – The fix to this is divine intervention – in witch case something would hinter you from killing your own mother before you were born, so that nature would bend the normal laws, to make sure A specifik historical line was being followed – Very unlikely .

    2) Either you cant go back in time, or humans will never find a way to control it ( or you can only go back for a very limited amount of time) if not … were are the folks from the future ?

    3) for the traveling faster than, or close to the speed of light – I think there is hope in that area (sub-space and what have you not ;) )

  6. alt thought. what if time travel doesn’t work simply because there isn’t anyway to displace/swap the space for what you’re sending back in time. Last i checked 2 objects cant occupy the same space at the same time. Send an object backwards, how do you displace the particles that are already in the spot you’re dropping the object?

    And low-ish brow thought. There’s a way to make light faster than ‘c’ , we’ve merely yet to discover it.

    And another thought I just had that ties to the first. No future time travelers visiting us since we don’t have any device able to accept the transmission. Think of trying to send a fax from a fax machine to a Morse Telegraph machine.

  7. Anyone who believes that time travel is possible probably also thinks that humans can reach the moon or that you could survive travelling at the speed of sound. Any scientific statement that anything is impossible should be prefaced by "given our current understanding of the universe … "

  8. "The main argument against time travel is based on the fact that the speed of light is fixed and that nothing can travel faster:"

    If this is so then why is it that light can never escape from a black hole?
    Scientists have stated previously that not even light can escape these phenomena.

  9. Firstly i dont believe that time exists, i believe the idea of time is used as a way of controlling society, i dislike how the calendar ignores pretty much everything before a so called date, i believe that travelling to a point of existence other than the one that you're in right now is possible.

    I believe that most of what is announced about how hard it would be to do certain things is simply lies, to keep the worlds population in the dark, it works too because by keeping people feeling not only trapped on this planet but trapped in your moment of existence you continue to look towards others for answers and if they say this cant be done then oddly people just accept that.

    Its likely that people and beings from other past and future moments (not time) are passing in and out, probably likely that passing between dimensions is happening too.

    The fake stories put out to encourage some to believe that the moon landing might have been fake is to lessen expectations, those controlling society though will have understanding far beyond anyones expectations.

  10. Didn't Stephen Hawkings already say this in 1992 when he presented the chronology protection conjecture? And is it odd to anyone else that this comes only 3 months after the Chinese Republic decided to ban all media related to time travel?

  11. So, we CAN (theoretically) travel at the speed of light? I think we should get that done first before we start worrying about time travel. Even if/when we can travel at "c" how much faster would you need to be to travel at the speed of time?

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